MartinC wrote:Toe overlap is a function of the frame design and many other things too so designing a frame that doesn't allow toe overlap is a tall order.
Not really. It's a moderately complex excercise in geometry that should be well within the capability of any competent design engineer. The real problem is that they can't easily get the forks and stems to go with that design due to the limited choice in offsets of both, the dimensions of which slavishly mimic what works for actual racing, where nobody uses mudguards, or goes slowly enough uphill to wobble, or has to negotiate cyclepath obstacles, etc.
Sure you can design a frame that doesn't have overlap for normal (i.e. exactly like me) people.
But quite often the designers fail - or are prevented by standard forks and stems in even that simple task!
If you design a frame that won't have overlap for a clown (in clown shoes) who rides with his heels on the pedals then we'll all be riding recumbent trikes.
I'll ignore that for now - but only for now.
Toe overlap in any given frame will depend on:
1- fork rake
2- rim size
3- tyre size
4- if and how mudguards are fitted
5- crank length
6- Q factor
7- foot size
8- shoe size and type
9- cleat position (laterally and fore/aft) if used
10- toe clip size if used
11- where the user decides to put their foot if flat pedals are used.
I've added numbers to this list to deal with it better.
1, 2, 3 and 4 are a function of the design of the bike and hence entirely within the designer's control. The correct fork offset is dictated by the head angle, fit something more than a few mm different and the bike will not handle as it should. Rim and tyre size is limited by the clearance, and it would be plain weird to fit a fatter tyre in front than the frame could handle just becasue the fork had more clearance. Nobody is suggesting that designers should cater for weird stuff (except you with your clowns
). Mudguards likewise are a matter of the design clearance and presence of fittings. No eyes, no clearance expected, is what the standards say already and that's fair enough.
6 does not vary enough to worry about and sufficiently predicted by the type of bike that type of frame is for.
5, 7 and 8 are a function of the size of rider a particular size of frame is for. A professional designer uses tables of anthropometric data to ensure that, for example, 90% of the relevant population segment are catered for. In cycling the limited range of available crank lengths makes his job easier in fact. Apart from clowns, the length of shoes does relate pretty well to the size of foot.
For 9 and 11 it is not necessary for a designer to cater for anything far off the known biomechanically optimum positioning.
Regarding 10: a thin steel toeclip adds insignificantly to the forward projection of the shoe alone. Plastic ones add something, but who still uses toeclips? I would not argue with a designer who said it was not necessary to take account of them.
However, if we're talking about the offer for sale of complete made-up bikes, which is what we were talking about regarding those Charge Mixers and it what the European Standards are about - not frames only - then the complete specification of the bike is fixed and known. This fixes most points of variation: 1,2,3,5,6 and 10, and makes 4 closely predictable. All that remains is the 90 percentile foot, hence shoe size and toe projection of the riders this bike is sized for - a simple matter of ergonomics.
It's not a difficult job to do if they want to do it. Given the motivation the designers will in turn demand from component suppliers the necessary close-up stems and forks with extra offset befitting the shallower head angles they'll have to use. They won't look exactly
like the bikes the pros ride in the Tour, but near enough that only you or I will spot the difference. And they will actually handle just as well. The factoid of poor handling with shallow head angles arises from putting a standard fork in such a frame. Fractionally longer front centres will improve the stopping distance, and 99.99% of those who buy ready-made bikes will never lean over far enough in a corner, or hold the bars steady enough while they do that, for a minuscule fraction less weight on the front wheel to make any diference at all to whether it washes out.
Toe overlap doesn't bother me but I can very well understand the concerns that others have even if I don't think there's a real problem. If you're a knowledgeable cyclist then you need to work out and remember what front centre distance you need on a bike. If you want to make a big fuss about it at point of sale then you'll probably just reinforce the prejudice that cycling's dangerous and should be banned. It's an amusing contradiction that we want safety regulations for a vehicle that can't even stay upright by itself! If we were logical we'd make full chaincases and stabilsers compulsory and ban foot retention devices.
There's nothing wrong with offering an informed choice and managing customer's expectations. I reject totally, your implication that those of us who do object to toe overlap are lacking in cycling skill. I certainly can ride a bike with overlap, sometimes I have to test ride them, but I don't like it and don't see why this should be foisted onto customers without so much as a by your leave. Yes, bicycles are fundamentally unstable vehicles, which makes it more rather than less important that unnecessary extra ways of falling off them are avoided - except by those who delight in circus tricks of course.
I just don't think it's worth having a standard for this - it'll either be meaningless or we'll stop a lot of people having perfectly sensible frames.
You're welcome to your opinion but I think you know in your heart of hearts that it isn't actually too difficult for a designer to ensure that 90% of the people buying a given size of complete bicycle, provided it is the right size for them and they ride it correctly, will not experience the problem. And for standards to address this is not difficult. They pretend to do it already and just need some sensible numbers to sort it out. This will probably force the standards writers to adopt a sliding-scale approach rather than one-size fits all, which will be a very good thing generally. (This aspect of the new standards has caused untold problems for manufacturers who've had to beef up perfectly good frame designs, so a small rider is lumbered with an overweight bike strong enough to carry someone twice their size - but that's another story!)
As for "perfectly sensible frames", these standards do not apply to frames alone, only complete bikes. Frames can be designed any which way and you are and forseeably will always be able to buy them, as frames. Frames don't get caught by any standards and Bicycle sales safety regulations unless they are first assembled into a bike and then sold by a retailer as a complete bike. If the frame and fork and other components of the customer's choosing are sold in one transaction, as bicycle parts, and the customer pays the shop separately to assemble them into a bike, there should be no problem.
However I think it would be better if there were provided a more obvious means for someone to buy complete bikes of a configuration that shops is not legally allowed to sell (even it some of them already do), such as one with the brake levers the other way round. Surely all it needs is a simple form for customers to sign to say they are aware of and agree to this, that and the other itemised deviations from the usual standard. No mass manufacturer is going to want those forms hanging around his bikes, so they'll all toe the line
. But it then becomes totally straightforward for the more specialist suppliers to offer something different, to meet unusual customer demands, to innovate and maybe push the design envelope in ways that eventually benefit the mainstream.